Table 2. Most frequent causes of microcephaly (congenital and postnatal).

CONGENITAL	POSTNATAL
Chromosome and/or genetics Trisomies of 13, 18 and 21 Cornelia de Lange syndrome Cri du Chat syndrome Smith-Lemli-Opitz syndrome	Chromosome and/or genetics Inborn errors of metabolism Mitochondrial diseases Aminoacidopathies Defects in glucose transport
AQUIRED	AQUIRED
Disruptive traumas Hypoxia or anoxia (insufficient placenta) Death of a twin (monochorionic)	Disruptive traumas Traumatic brain injury Parenchymal hemorrhage (more common in preterm children) Hypoxia or anoxia
Infections and protozooses Syphilis Toxoplasmosis Rubella Cytomegalovirus Herpes simplex Parvovirus B19 Zika virus Other viruses	Infections Meningitis Encephalitis
Teratogens/clinical conditions Alcohol Hydantoin Drugs (cocaine, crack, among others) Radiation Maternal diabetes mellitus without adequate control Maternal phenylketonuria	Toxins Copper poisoning Chronic renal failure
Deprivation Maternal hypothyroidism Folic acid insufficiency Malnutrition Insufficient placenta	Deprivation Hypothyroidism Malnutrition Anemia Congenital cardiopathy

Note: Adapted and modified from Ashwal et al.,52 Abuelo.58